The general objective of the five-year research program is the study of structural and functional bases for the neuronal operations of the cerebellar cortex in different vertebrate species. The design of experiments will be such that a developmental trend in a phylogenetical sense is stressed throughout the research. On the basis of these studies, the different neuronal organizations in various cortices will be ascertained, the ultimate aim being a) further understanding of the role of the cerebellum in regulation of movement, and b) the utilization of the cerebellar cortex as a model for central nervous system organization. The techniques utilized will involve standard and special electrophysiological techniques comprising intra- and extracellular recordings from anesthetized preparations, as well as multielectrode recording in unanesthetized conditions. The analysis of this data will be carried out on the basis of unitary and field potentials as well as by means of current density analysis. Mathematical models will be derived from the field potentials obtained in these studies. From a morphological point of view, study will comprise light and electron microscopical techniques as well as histochemical techniques at both levels.